Refactor VMTagScope to Thread* rather than Isolate*.

runtime/vm/flow_graph_builder.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/flow_graph_builder.h"
 
 #include "lib/invocation_mirror.h"
 #include "vm/ast_printer.h"
 #include "vm/bit_vector.h"
 #include "vm/class_finalizer.h"
@@ skipping 4766 matching lines @@
   exit_ = for_finally_block.exit_;
 }
 
 
 void EffectGraphVisitor::VisitStopNode(StopNode* node) {
   AddInstruction(new(Z) StopInstr(node->message()));
 }
 
 
 FlowGraph* FlowGraphBuilder::BuildGraph() {
-  VMTagScope tagScope(Thread::Current()->isolate(),
+  VMTagScope tagScope(Thread::Current(),
                       VMTag::kCompileFlowGraphBuilderTagId,
                       FLAG_profile_vm);
   if (FLAG_print_ast) {
     // Print the function ast before IL generation.
     AstPrinter::PrintFunctionNodes(parsed_function());
   }
   if (FLAG_print_scopes) {
     AstPrinter::PrintFunctionScope(parsed_function());
   }
   TargetEntryInstr* normal_entry =
@@ skipping 34 matching lines @@
   Report::MessageF(Report::kBailout,
                    Script::Handle(function.script()),
                    function.token_pos(),
                    "FlowGraphBuilder Bailout: %s %s",
                    String::Handle(function.name()).ToCString(),
                    reason);
   UNREACHABLE();
 }
 
 }  // namespace dart